#version 330 core
struct Material{
  vec3 ambient;
  vec3 diffuse;
  vec3 specular;
  float shininess; // 反光度
};

struct Light{
  vec3 position;

  vec3 ambient;
  vec3 diffuse;
  vec3 specular;
};

out vec4 FragColor;

uniform Material material;
uniform Light light;

uniform vec3 viewPos;

in vec3 Normal;
in vec3 FragPos;

void main()
{
  //ambient
  vec3 ambient = light.ambient * material.ambient;

  //diffuse
  vec3 norm = normalize(Normal);
  vec3 lightDir = normalize(light.position - FragPos);
  float diff = max(dot(norm, lightDir), 0.0f);
  vec3 diffuse = light.diffuse * (diff * material.diffuse);

  //specular
  vec3 viewDir = normalize(viewPos - FragPos);
  vec3 reflectDir = reflect(-lightDir, norm);
  float spec = pow(max(dot(viewDir, reflectDir), 0.0f), material.shininess);
  vec3 specular = light.specular * (spec * material.specular);

  //all
  vec3 result =  ambient + diffuse + specular;
  FragColor = vec4(result, 1.0f);

}
